"Full Tree: used in Competition, Super Stock, and Stock, for which a handicap starting system is used to equalize competition. The three amber bulbs on the Christmas Tree flash consecutively five-tenths of a second apart, followed five-tenths later by the green starting light. A perfect reaction time on a full Tree is .500."
Maybe the .500 light applys only to actual head to head racing, rather than just test and tune, "Run Whatcha Brung" sorta thing? Like I said earlier, it may depend on who's sanctioning the event?
Weight plays in here heavily. One of my customers with an 87 notch that weighed 3100# w/o him ran 12.7@107mph on a stock cam, ported heads, ported stock lower, stock upper and TB with long tubes. He was a very good driver too. HIs dyno was 242RWHP and 292RWTQ. The one who made 255RWHP & 311RWTQ ran 13.9@100mph because he has a heavy 95GT.